WILD ABOUT TEXAS: Harvester ants help boost quality of soil

Spring has definitely sprung! All about town residents can be seen working diligently in their yards to improve the landscape. Unbeknownst to most people, there is a small animal that actually improves the quality of the soil in the yard, although this animal is known to pack quite a punch with its venomous sting. This animal is the harvester ant (Pogonomyrmex sp.).

Harvester ants can be found throughout the American Southwest, from California to East Texas. Their natural range happens to coincide with that of the horned lizard (also known as "horny toads"), and this species of ant is the chief prey item for these lizards. In areas where harvester ants have been exterminated, horned lizards have had the same fate.

Harvester ants, like all other ant species, are nothing more than wingless wasps that live in colonies. This variety of ant is the largest species in West Texas, with workers averaging of an inch in total length. The queen of the colony is slightly larger, averaging nearly half an inch. The general coloration of this ant ranges from a dark brick red to almost candy-apple red.

These ants are insects, and like others of this group, they have three body parts: the head, the thorax and the abdomen. Each one of these body parts has a specific purpose, with the head being home to the eyes, antennae and feeding appendages, the thorax being where the legs and wings are attached, and the abdomen being where the majority of the internal organs are housed.

Also like others in the insect group, the skeletal structure is on the outside of the ant's body. This structure is known as the exoskeleton. This ant has six legs, and some members of the colony (known as the alates) have two pairs of wings that are used for flight.

Like most other species of ants, harvester ants live in surprisingly large colonies. It has been estimated that a particular nest may house over 20,000 individuals!

The colony is accessible by only a single nest opening, and all plant matter, including root systems, is cleared away around it. This perimeter is about 3 feet or so, making the nest easily recognizable.

The nest itself can descend for 20 feet below the surface, and there are many times multiple side systems that can extend out for a dozen or more feet. The benefits of a single nest are obvious, the most important being the aeration of the landscape that adds to the welfare of the soil.

Only the females of these colonies are active, at least until the seasonal rains come and the "royal" members of the group ascend to the surface to swarm. Their purpose in doing so is to leave that colony and begin another.

Harvester ants are seed gathers. Many trails from the nest opening to rich food sources can be observed. Although this species feeds on seeds, harvester ants can and will sting perceived predators with a toxin that can cause as severe a pain as any other insect in this area. The sting from this species is several times as painful as the more common and invasive fire ant.

Generally, they are content to go about their business casually, but they are very quick to defend their nest from potential threats, with many individuals emerging from the nest at the slightest provocation.

Give this species adequate space and use common sense when near the nest, and allow these native arthropods to improve the welfare of your yard in ways that only nature could design.

Michael Price is the director of the San Angelo Nature Center. Contact him at michael.price@sanangelotexas.us.